Coal tar distillates and processes of preparing the same



. anthracene.

2,033,547. PATENT OFFICE COAL TAR DISTILLATES AND PROCESSES OF PREPARING THE SAME Anderson W. Ralston, Chicago, 111., assignor to Armour and Company, Chicago, Ill., acorporation of Illinois No Drawing. Application August 21, 1935,

Serial No.'37,263

/ 16 Claims.

as a new product a coal tar distillate containing constituents crystallizing at low temperatures to which has been added a small amount of a Friedel-Crafts reaction product from a fatty acid chloride and a coal tar fraction, whereby the crystallization of said crystallizable constituents is inhibited, and it further comprises processes of preventing crystallization at low temperatures in coal tar compounds.

A great many kinds of coal tar distillates are used in the arts. Tar acids, for example, are used as disinfectants, insecticides, and so forth. These distillates are used in wood preservation, in spray oils, for saturating roofing felt, as a binder in asphalt and tar macadam roads, and also as an aqueous emulsion for sprinkling roads as a dust preventative. I

Many .of these coal tar distillates contain quantities of naphthalene, anthracene, and other hydrocarbons which are normally solid. For example, that fraction of coal tar boiling up to 200 C. will contain considerable quantities of naphthalene. Those distillates boiling at 270 C. and over will contain considerable quantities of Still other distillates, for example, those having a boiling point range of 200 C. to 300 C. will-contain twelve or more percent 0 naphthalene.

In the customary treatment of these distil-- lates to fit them for use in the arts, it is cornmon to go to an expensive treatment to remove naphthalene and anthr'acene. For example, the heavy 'oil fraction of the coal tar is run into shallow tanks or pans and allowed to cool down whereupon the larger part of the naphthalene crystallizes out. The oil is separated from the crystals and very often given a further chilling" at temperatures as low as -10 F. to remove additional quantities of naphthalene, anthracene, and other substances crystallizable at low temperatures. I

It has always been considered desirable to free the normally liquid coal tar distillates of their content of substanceswhich crystallize at low temperatures. Many of these distillates are, as stated, used as spray oils. If the distillate were not'freed of its crystallizable content the crystals would, at low temperatures met with in use, clog the spray nozzles. In many other industrial applications of these distillates low working temperatures, such as winter weather, are common. In the application of road oils, for example, and more especially the application of these distillates for preserving, it is essential that the distillates used have low cold tests. ,This means that at temperatures as low as 0* F., or

- -10 F., very little naphthalene or anthracene should be present to crystallize. This hitherto This invention relates to coal tar distillates and processes of preparing the same and it comprises has only been achieved by freeing the distillate of most of its naphthalene and anthracene coninhibit thecrystallization of naphthalene, an-

thracene, phenanthrene, and the many other normally solid hydrocarbon constituents in coal tar distillates. Because I have been enabled to-inhibit the crystallization of these constituents, it is unnecessary for me to use the expensive purification process hitherto employed to free these distillates of crystallizable constituents. I can simply permit the naphthalene to crystallize out of a heavy oil, for example, at room temperature in the ordinary way used for recovering naphthalene, and then add to the heavy oil one of the crystallization inhibitors of the present invention. In other words I need not subject the heavy oil, after preliminary separation of naphthalene therefrom, to freezing temperatures to remove thecontent of crystalli'zable constituents which, while it remains dissolved in the liquid distillate at normal temperatures (20 (3.), crystallizes at lower temperatures.

Many of the coal tar distillates used in the arts have been applied in a heated condition to roads, wood, and so forth merely to avoid the clogging of devices used in the application of these materials. One of the advantages of my invention is that I can apply such distillates at crystallization inhibiting properties of a broad class of compounds which have been specifically described and claimed in the copending applications of. Ralston, Christensen and Bauer Serial Number 29,422, filed July 1, 1935. These substances can be generically defined as a Friedel- Crafts reaction product from a fatty acid having at least six carbon atoms and a coal tar fraction, the major portion of which boils above about 200 C. All of these compounds are new materials. They are either free flowing oils or waxy solids of unknown constitution. They are all made by reacting a coal tar fraction, the major portion of which boils above 200 0., with a fatty acid chloride having at least six carbon atoms.

dissolved in carbon disulflde and in the presence of aluminum chloride as acatalyst. The method I can use any of the fatty acid chlorides'having' six or more carbon atoms. Generally I start with s'tearyl chloride but I am not limited thereto.

For example, as pointed out in the aforesaid application, I can react so-called crude tower bottoms, which have a boiling point range of about 230 C. to 375 C., with stearyl chloride. Instead of starting with the crude tower bottoms I can start with variousfractions thereof. One,

of the very best coal tar fractions to use as a starting material is .that known as red wax. It

is a distillate having a boiling point range of approximately 432? O. to 500 C. In still other instances I start with heavy coal tar bases.

All of these coal tar fractions can be made to react with fatty acid chlorides having six or more carbon atoms to give products which are useful in the present invention. I shall give one example of how these products are made,

it being understood, however, that in each inmixture refluxed at 46 C. The reaction mixture is then poured into a mixture of ice and hydrochloric acid to hydrolyze the complex aluminum chloride compound. Carbon disulilde is next removed by steam distillation and the hydrolysis completed by means of steaming. The product obtained is dark red oil floating on the aqueous reaction mixture. This oil is removed and dried and then added to the coal tar distillate to be treated.

I shall now give various examples of the treatment of various coal tar distillates to inhibit crystallization therein. One distillate which is used to considerable extent in the arts is that known as high chill tar acid oil". I determine the extent of crystallization in this and other distillates in the following manner. A small sample of the distillate is placed in a testiar and a thermometer immersed into the liquid. The test Jar with its contents is then cooled and the extent of crystallization noted as the temperature or the distillate decreases. In the case of high chill tar acid oil a two inch column thereof in the test Jar develop crystals at 0 F. At 20 F. the column contains one inch of crystals, and the sample under test pours very sluggishly. At -25 F. the material freezes to a solid crystallized mass. On allowing the temperature to rise to 0 F. the sample still'contains 1% inches of wacrystals and it is necessary to permit the sample towarmupto55F.beforeallofthecrystals will disappear.

By the present invention I am able to markedly products noted above to the high chill tar acid oil. For example, I add 0.5 percent of that reaction product made from coal tar distillates boiling between 450C. and 500 C., and stearyl chloride. I have described this product in specific details above. After adding 0.5 percent of the reaction product to the high chill tar acid oil, I find that only very slight crystallization occurs at 15" F. and at 25 F. the under test contains only about of an inch of crystals. When the temperature of the sample is allowed to rise to 5 F. practically all of the crystals disappear. This means that by the practice of the present invention I am able to reduce the cold test of high chill ,tar acid oil to a marked extent.

In another example of my invention I add about 0.5 percent of the above Friedel-Crafts reaction product to an acid coal tar distillate showing initiahcrystallization at 0 F. and turning solid at 20 F. After addition of the reaction product no crystallization appears until 20 F. and solidification does not occur until the temperature is reduced to -30 F.

In another example I add about 0.5 percent of the above described Friedel-Crafts reaction product to a coal tar distillate having a boiling range of 300 C. to 375 C. This coal tar distillate, in the absence of the added crystallization inhibitor shows initial crystallization at 45 F. and turns solid at 30 F. Upon the addition of 0.5 percent of the reaction product initial crystallization does not develop until the temperature has been reduced to 30 F. and the sample does not turn solid until the temperature is reduced .to 15 F. This coal tar distillateis a material containing a very large quantity of naphthalene,

much more than is ordinarily desirable. I have indicated the results to be expected with materials of this type in order to show the effectiveness of my crystallization inhibitors.

As stated above my invention is applicable to the improvement of all normally liquid coal tar distillates containing substances tending to crystallize when the temperature of the distillate is reduced. I did not wish to be restricted to the treatment of any specific distillate. And, as

stated above, I can use many different Friedel Crafts reaction products. Any of those described in the aforesaid copending application can be used.

Coal'tar fraction starting material Character of reaction product Crude tower bottoms Fractionated crude tower bottoms fraction B. P. R. 3l5330 C.

flowing oil. Dark viscous brown oil.

Fractionated crude tower bottoms Dark brown grease.

fraction B. P. R. 330-345" C.

Alkali washed tower bottoms.- Greenish brown viscous oil.

Acid wuhed tower bottoms Light reddish-brown grease.

Acid washings from crude tower Brown waxy solid.

bottoms. Acid and alkali washed tower Dark red, waxy oil.

bottoms. Crude red wax Hard dark red solid. Acid washed red wax" Dark red wax. Light coal tar bases. Dark red greasy solid. Heavy coal tar bases Dark red greasy solid. Crude anthracsne I--- Red, waxy material. Add washed u-ude anthraoono Dark red oil. Cocal tar distillate B. P. B. 300-375 Rod free-flowing oil. CoaltsrdistillateERRAW Rodviscous oil. Creosots oil residue Brown viscous oil. Fractionated creosote oil residue Roddish brown oil.

B. P. Ram-250 O.atl0mm.

Heavy reddish-brown freo- In the above table, B. P. R. stands for boiling point range. The acid and alkali washed tower bottoms refer-to tower bottoms from which acid soluble and alkali soluble constituents have been removed by washing with acids or alkalies. The same applies to acid washed red wax. The coal tar bases, crude anthracene and creosote oil residues are well-known commercial coal tar fractions,

It is understood, of course, that the Friedel- Crafts reaction products are made from the various coal tar fractions by the same general procedure described in detail above.

Although I have referred more specifically to the addition of about 0.5 percent of the reaction product to the coal tar distillates, it is understood that this quantity can vary over wide limits, from about 0.1 percent to as much as percent. More than 5 percent is not particularly advantageous since the'inhibiting action is not generally increased. But those skilled in the art will know that trialswith various quantities of inhibitor should be made until the correct amoun for the distillate in question is reached. 1

Having thus described my invention, what I claim is:

' lization, the inhibitor being a Friedel-Crafts re action product from a coal tar fraction and a fatty acid chloride having at least six carbon atoms.

2. A liquid coal tar distillate containing solid constiutents crystallizing upon reducing the temperature of said distillate, and a small amount of a crystallization inhibitor to inhibit said crystallization, the inhibitor being a Friedel-Crafts reaction product from a coal tar fraction having a boiling range of about 400 C. to 500 C. and a fatty acid chloride having at least six carbon atoms.

3. A liquid coal tar distillate containing solid constituents crystallizing upon reducing the temperature of said distillate, anda small amount of a crystallization inhibitor to inhibit said crystallization, the inhibitor being a Friedel-Crafts reaction product from a coal tar fraction known as red wax and a fatty acid chloride having at least six carbon atoms.

"4. A liquid coal tar distillate containing solid constituents crystallizing upon reducing the temperature of said distillate, and a small amount of a crystallization inhibitor to inhibit said crystallization, the inhibitor beng a Friedel-Crafts reaction product, from a coal tar fraction the major portion of which boils above 200 C. and a fatty acid chloride having at least six carbon atoms.

5. The product as in claim 1 wherein the chloride is stearyl chloride.

6. The product as in claim 2 wherein the ch ride is stearyl chloride.

7. The product as in claim 3 wherein the chloride is stearyl chloride.

8. The product as in claim 4 wherein the chloride is stearyl chloride.

9. The method of inhibiting crystallization in liquid coal tar distillates normally tending to develop crystals on cooling which includes adding to the distillate a crystallization inhibitor comprising a Friedel-Crafts reaction product from a coal tar fraction and a fatty acid chloride having at least six carbon atoms. 7

10. The method of inhibiting crystallization in liquid coal tar distillates normally tending to develop crystals on cooling which includes adding to the distillate a crystallization inhibitor comprising a Friedel-Crafts reaction product from a coal tar fraction having a boiling range of about 400 C. to 500 C. and a fatty acid chloride having at least six carbon atoms.

11. The method of inhibiting crystallization in liquid coal tar distillates normally tending to develop crystals on cooling which includes adding to the distillate a crystallization inhibitor comprising a Friedel-Crafts reaction'product from a coal tar fraction known as red wax and a fatty acid chloride having at least six carbon atoms.

12. The method of inhibiting crystallization in liquid coal tar distillates normally tending to develop crystals on cooling which includes adding to the distillate a crystallization inhibitor comprising a Friedel-Crafts reaction product from a coal tar fraction, the major portion of which boils above 200 C. and a fatty acid chloride having at least six carbon atoms.

13. The process as in claim 9 wherein the chloride is stearyl chloride.

1 1. The process as in claim 10 wherein the chloride is stearyl chloride.

15. The process as in claim 11 wherein the chloride is stearyl chloride.

16. The process as in claim 12 wherein the chloride is stearyl chloride.

ANDERSON W. RALSTON. 

